Bet‐hedging as a complex interaction among developmental instability,environmental heterogeneity,dispersal, and life‐history strategy

One potential evolutionary response to environmental heterogeneity is the production of randomly variable offspring through developmental instability, a type of bet‐hedging. I used an individual‐based, genetically explicit model to examine the evolution of developmental instability. The model considered both temporal and spatial heterogeneity alone and in combination, the effect of migration pattern (stepping stone vs. island), and life‐history strategy. I confirmed that temporal heterogeneity alone requires a threshold amount of variation to select for a substantial amount of developmental instability. For spatial heterogeneity only, the response to selection on developmental instability depended on the life‐history strategy and the form and pattern of dispersal with the greatest response for island migration when selection occurred before dispersal. Both spatial and temporal variation alone select for similar amounts of instability, but in combination resulted in substantially more instability than either alone. Local adaptation traded off against bet‐hedging, but not in a simple linear fashion. I found higher‐order interactions between life‐history patterns, dispersal rates, dispersal patterns, and environmental heterogeneity that are not explainable by simple intuition. We need additional modeling efforts to understand these interactions and empirical tests that explicitly account for all of these factors.     

Host‐parasite coevolution can promote the evolution of seed banking as a bet‐hedging strategy

Seed (egg) banking is a common bet‐hedging strategy maximizing the fitness of organisms facing environmental unpredictability by the delayed emergence of offspring. Yet, this condition often requires fast and drastic stochastic shifts between good and bad years. We hypothesize that the host seed banking strategy can evolve in response to coevolution with parasites because the coevolutionary cycles promote a gradually changing environment over longer times than seed persistence. We study the evolution of host germination fraction as a quantitative trait using both pairwise competition and multiple mutant competition methods, while the germination locus can be genetically linked or unlinked with the host locus under coevolution. In a gene‐for‐gene model of coevolution, hosts evolve a seed bank strategy under unstable coevolutionary cycles promoted by moderate to high costs of resistance or strong disease severity. Moreover, when assuming genetic linkage between coevolving and germination loci, the resistant genotype always evolves seed banking in contrast to susceptible hosts. Under a matching‐allele interaction, both hosts’ genotypes exhibit the same seed banking strategy irrespective of the genetic linkage between loci. We suggest host–parasite coevolution as an additional hypothesis for the evolution of seed banking as a temporal bet‐hedging strategy.     

Low and annually variable migratory connectivity in a long‐distance migrant: Whinchats Saxicola rubetra may show a bet‐hedging strategy

The spatial scale of non‐breeding areas used by long‐distance migrant animals can vary from specific, relatively small non‐breeding areas for each independent breeding population (high connectivity) to a distribution over a large non‐breeding area with mixing of breeding populations (low connectivity). Measuring variation in the degree of connectivity and how it arises is crucial to predict how migratory animals can respond to global habitat and climate change because low connectivity is likely to be an adaptation to environmental uncertainty. Here, we assess whether use of non‐breeding areas in a long‐distance migrant may be stochastic by measuring the degree of connectivity, and whether it is annually variable. Twenty‐nine wintering Whinchats tagged with geolocators over 2 years within 40 km² in central Nigeria were found to be breeding over 2.55 million km² (26% of the land area of Europe), without an asymptote being approached in the relationship between area and sample size. Ranges differed in size between years by 1.51 million km² and only 15% of the total breeding range across both years overlapped (8% overlap between years when only first‐year birds were considered), well above the range size difference and below the proportion of overlap that would be predicted from two equivalent groups breeding at random locations within the observed range. Mean distance between breeding locations (i.e. migratory spread) differed significantly between years (604 ± 18 km in 2013 and 869 ± 33 km in 2014). The results showed very low and variable connectivity that was reasonably robust to the errors and assumptions inherent in the use of geolocators, but with the caveat of having only ranges of 2 years to compare, and the sensitivity of range to the breeding locations of a small number of individuals. However, if representative, the results suggest the scope for between‐year variation (cohort effects) to determine migrant distribution on a large scale. Furthermore, for species with similarly low connectivity, we would predict breeding population trends to reflect average conditions across large non‐breeding areas: thus, as large areas of Africa become subject to habitat loss, migrant populations throughout Europe will decline.     

Mate‐choice copying by females: the advantages of a prudent strategy

Mate choice by females may be influenced by both advertizing traits of males, and behaviour of other females. Here, a simple genetic and behavioural model studies the advantages of mate‐choice copying. From a genetic point of view, a female preferring to copy others’ mate choice adopts a prudent strategy, because her offspring will inherit the same alleles from their father as the other young in the population. The model predicts that a female should copy others’ mate‐choice, unless she encounters a relatively more attractive male than the one she has observed mating, and the attractiveness of the male reflects his genotype. For low or moderate reliability of male signalling, mate‐copying is always predicted, even if the newcoming male is more attractive than the first male. This effect is attenuated, however, when the number of females that have already chosen the first male increases.     

Obligate annual and successive facultative diapause establish a bet‐hedging strategy of Rhagoletis cerasi (Diptera: Tephritidae) in seasonally unpredictable environments

To cope with temporal and spatial heterogeneity of habitats, herbivorous insects in the temperate zone usually enter diapause that facilitates synchronization of their life cycle with specific stages of host plants, such as fruit ripening. In the present study, we address those factors regulating dormancy responses as part of a ‘longer strategy’ to persist and thrive in temperate environments, focusing on Rhagoletis cerasi, a univoltine, oligophagous species, which overwinters as pupae and emerges when host fruits are available for oviposition at local scale. To ensure population survival and reproduction at habitats with ecological heterogeneity, R. cerasi has evolved a sophisticated diapause strategy based on a combination of local adaptation and diversified bet‐hedging strategies. Diapause duration is determined both by (i) the adaptive response to local host fruit phenology patterns (annual diapause) and (ii) the plastic responses to unpredictable inter‐annual (temporal) climatic variability that drives a proportion of the populations to extend dormancy by entering a second, successive, facultative cycle of prolonged diapause as part of a bet‐hedging strategy. Besides the dormant periods, post‐diapause development (which varies among populations) exerts ‘fine tune’ adjustments that assure synchronization and may correct possible errors. Adults emerging from pupae with prolonged diapause are larger in body size compared with counterparts emerging during the first year of diapause. However, female fecundity rates are reduced, followed by an extended post‐oviposition period, whereas adult longevity remains unaffected. Overall, it appears that R. cerasi populations are adapted to ecological conditions of local habitats and respond plastically to unpredictable environmental (climatic) conditions.     

Hydrological responses of a valley‐bottom wetland to land‐use/land‐cover change in a South African catchment: making a case for wetland restoration

Valley‐bottom wetlands are valuable assets as they provide many ecosystem services to mankind. Despite their value, valley‐bottom wetlands are often exploited and land‐use/land‐cover (LULC) change results in trade‐offs in ecosystem services. We coupled physically based hydrological modeling and spatial analysis to examine the effects of LULC change on water‐related ecosystem services in the Kromme catchment: an important water‐providing catchment for the city of Port Elizabeth. LULC scenarios were constructed to match 5 different decades in the last 50 years to explore the potential effects of restoring the catchment to different historic benchmarks. In the Kromme catchment, valley‐bottom wetlands have declined by 84%, driven by key LULC changes: an increase in irrigated land (307 ha) and invasion by alien trees (336 ha). If the wetlands were restored to the relatively pristine extent and condition of the 1950s, riverflow could increase by approximately 1.13 million m³/a, about 6% of the current supply to Port Elizabeth. Wetland restoration would also significantly improve the catchment's ability to absorb extreme rainfall events, decreasing flood damage. We conclude that in the face of the water scarcity in this region, all ecosystem services, particularly those related to water flow regulation, should be taken into account by decision makers in charge of land zonation. Zonation decisions should not continue to be made on the basis of provisioning ecosystem services alone (i.e. food provision or dam yield). We recommend prioritization of the preservation and restoration of valley‐bottom wetlands providing water‐related ecosystem services to settlements downstream.     

Water–energy,land‐cover and heterogeneity drivers of the distribution of plant species richness in a mountain region of the European Alps

Aim To evaluate the relative importance of water–energy, land‐cover, environmental heterogeneity and spatial variables on the regional distribution of Red‐Listed and common vascular plant species richness. Location Trento Province (c. 6200 km²) on the southern border of the European Alps (Italy), subdivided regularly into 228 3′ × 5′ quadrants. Methods Data from a floristic inventory were separated into two subsets, representing Red‐Listed and common (i.e. all except Red‐Listed) plant species richness. Both subsets were separately related to water–energy, land‐cover and environmental heterogeneity variables. We simultaneously applied ordinary least squares regression with variation partitioning and hierarchical partitioning, attempting to identify the most important factors controlling species richness. We combined the analysis of environmental variables with a trend surface analysis and a spatial autocorrelation analysis. Results At the regional scale, plant species richness of both Red‐Listed and common species was primarily related to energy availability and land cover, whereas environmental heterogeneity had a lesser effect. The greatest number of species of both subsets was found in quadrants with the largest energy availability and the greatest degree of urbanization. These findings suggest that the elevation range within our study region imposes an energy‐driven control on the distribution of species richness, which resembles that of the broader latitude gradient. Overall, the two species subsets had similar trends concerning the relative importance of water–energy, land cover and environmental heterogeneity, showing a few differences regarding the selection of some predictors of secondary importance. The incorporation of spatial variables did not improve the explanatory power of the environmental models and the high original spatial autocorrelation in the response variables was reduced drastically by including the selected environmental variables. Main conclusions Water–energy and land cover showed significant pure effects in explaining plant species richness, indicating that climate and land cover should both be included as explanatory variables in modelling species richness in human‐affected landscapes. However, the high degree of shared variation between the two groups made the relative effects difficult to separate. The relatively low range of variation in the environmental heterogeneity variables within our sampling domain might have caused the low importance of this complex factor.     

A critique of 'countryside biogeography' as a guide to research in human‐dominated landscapes

Proliferation of redundant terms in ecology and conservation slows progress and creates confusion. ‘Countryside biogeography’ has been promoted as a new framework for conservation in production landscapes, so may offer a replacement for other concepts used by landscape ecologists. We conducted a systematic review to assess whether the 'countryside biogeography' concept provides a distinctive framing for conservation in human‐dominated landscapes relative to existing concepts. We reviewed 147 papers referring to countryside biogeography and 81 papers that did not. These papers were divided into categories representing three levels of use of countryside biogeography concepts (strong, weak, cited only) and two categories that did not use countryside biogeography at all but used similar concepts including fragmentation and matrix. We revealed few distinctions among groups of papers. Countryside biogeography papers made more frequent use of the terms 'ecosystem services', 'intensification' and 'land sparing' compared with non‐countryside biogeography papers. Papers that did not refer to countryside biogeography sampled production areas (e.g. farms) less often, and this related to their focus on habitat specialist species for which patch‐matrix assumptions were reasonable. Countryside biogeography offers a conceptual wrapper rather than a distinctive framework for advancing research in human‐modified landscapes. This and similar wrappers such as ‘conservation biogeography’ and ‘agricultural biogeography’ risk creating confusion among new researchers, and can prevent clear communication about research. To improve communication, we recommend using the suite of well‐established terms already applied to conservation in human‐modified landscapes rather than through an interceding conceptual wrapper.     

Limited use of bat boxes in a rural landscape: implications for offsetting the clearing of hollow‐bearing trees

Bat boxes frequently form part of hollow‐bearing tree offsets; however, their effectiveness is poorly documented. We investigated the effectiveness of a bat box program designed to partially offset tree hollow loss from clearing for a coal mine. During the first year of monitoring, we detected bats in 5% of 1,308 box checks. Only 3 of 13 local tree cavity‐roosting bat species/species groups used boxes and occupancy was not strongly associated with modeled box and site attributes. In the second year, we tested two hypotheses that may explain the relatively low box use: (1) solar exposure of boxes was inadequate for heterothermic bats and (2) available box designs were of low suitability. Relocating boxes to increase solar exposure did not increase use, or enhance the temperature profiles of relocated boxes. Introduction of a new box design led to 11 times higher use compared with existing designs for Nyctophilus spp. (long‐eared bat). Overall, our data suggest that the bat box program was ineffective due to few bat species using boxes, infrequent box use by three species, and rarity of maternity roosting. The knowledge gap of species‐specific box designs and roosting ecology limits the effectiveness of boxes to offset cleared hollow‐bearing trees. Lack of knowledge and the widespread use of bat boxes to offset lost tree hollows highlights the need to (1) rigorously protect hollow‐bearing trees and (2) advance our understanding of species‐specific roost ecology, box design preferences and mechanical hollow creation into trees, before artificial hollows can be considered a meaningful offset measure.     

Broad‐substrate screen as a tool to identify substrates for bacterial Gcn5‐related N‐acetyltransferases with unknown substrate specificity

Due to a combination of efforts from individual laboratories and structural genomics centers, there has been a surge in the number of members of the Gcn5‐related acetyltransferasesuperfamily that have been structurally determined within the past decade. Although the number of three‐dimensional structures is increasing steadily, we know little about the individual functions of these enzymes. Part of the difficulty in assigning functions for members of this superfamily is the lack of information regarding how substrates bind to the active site of the protein. The majority of the structures do not show ligand bound in the active site, and since the substrate‐binding domain is not strictly conserved, it is difficult to predict the function based on structure alone. Additionally, the enzymes are capable of acetylating a wide variety of metabolites and many may exhibit promiscuity regarding their ability to acetylate multiple classes of substrates, possibly having multiple functions for the same enzyme. Herein, we present an approach to identify potential substrates for previously uncharacterized members of the Gcn5‐related acetyltransferase superfamily using a variety of metabolites including polyamines, amino acids, antibiotics, peptides, vitamins, catecholamines, and other metabolites. We have identified potential substrates for eight bacterial enzymes of this superfamily. This information will be used to further structurally and functionally characterize them.     

Canopy manipulation as a tool for restoring mature forest conifers under an early‐successional angiosperm canopy

Low‐light environments in early‐successional forests that have established after abandonment of farming often restrict the establishment of later successional species resulting in an arrested succession. This 6‐year study tested the potential of different canopy manipulations to facilitate the establishment of a light‐demanding canopy tree species, tōtara (Podocarpus totara), within a regenerating kānuka (Kunzea robusta) stand. Results highlighted the effectiveness of artificial gaps over other methods (ring‐barking and edge‐planting) in accelerating the growth of planted tōtara. Seedlings under gaps grew consistently taller and faster over time indicative of an improved understorey light environment. Ring‐barking did not have a significant effect on tōtara growth because only a portion of the treated trees died, and after 6 years dead trees remained standing with intact branches resulting in insignificant increases in light transmission. At the forest edge sites, tōtara growth was highly variable. Although some seedlings grew as tall as in the gaps, others did not. Survival was also lower in the edge sites than in other treatments, which was likely due to enhanced herbivory from ungulates which impacted some plants at these sites. Gap creation is likely to be an important tool for restoring late‐successional canopy species in regenerating stands both through providing ideal sites for the growth of light‐demanding species such as tōtara and through natural establishment of other future canopy trees into the gaps.     

Assessment of a Multi‐Species Planting Approach for Restoring Thick‐Mat Floating Marsh,Louisiana, U.S.A.

Planting multiple species in wetland restoration sites could potentially accelerate ecological succession while enhancing ecological services. Our study of thick‐mat floating marsh demonstrated that two species performed better than monocultures for developing a more structurally sound root mat. Although Panicum hemitomon is the typical dominant and focal species of all restoration efforts of this habitat type, we evaluated the effects of additional species, including Sagittaria lancifolia, a ubiquitous floating marsh constituent, and three laterally growing specialists (Alternanthera philoxeroides, Hydrocotyle ranunculoides, and Ludwigia peploides). In a mesocosm experiment, we found greater P. hemitomon biomass in monocultures but greater vegetative cover and total mat biomass with P. hemitomon plus L. peploides, but not greater biomass in the most species‐rich treatment or treatment with the greatest initial planting density. We conclude that L. peploides aids restoration of thick‐mat floating marsh by increasing mat buoyancy, enhancing lateral growth, and providing greater root mat structural integrity. This type of laterally growing specialist should accelerate coalescence of neighboring constructed and naturally formed mats. Planting species that occupy complementary niches should also minimize competition for key resources.     

Targeting EZH2 as a novel therapeutic strategy for sorafenib‐resistant thyroid carcinoma

Thyroid carcinoma is the most common endocrine malignancy. Surgery, post‐operative selective iodine‐131 and thyroid hormone suppression were the most common methods for the therapy of thyroid carcinoma. Although most patients with differentiated thyroid carcinoma (DTC) showed positive response for these therapeutic methods, some patients still have to face the radioactive iodine (RAI)‐refractory problems. Sorafenib is an oral multikinase inhibitor for patients with advanced RAI refractory DTC. However, the side effects and drug resistance of sorafenib suggest us to develop novel drugs and strategies for the therapy of thyroid carcinoma. In this study, we firstly found that patients with sorafenib resistance showed no significant change in rapidly accelerated fibrosarcoma and VEGFR expression levels compared with sorafenib sensitive patients. Moreover, a further miRNAs screen by qRT‐PCR indicated that miR‐124‐3p and miR‐506‐3p (miR‐124/506) were remarkably reduced in sorafenib insensitive patients. With a bioinformatics prediction and functional assay validation, we revealed that enhancer of zeste homolog 2 (EZH2) was the direct target for miR‐124/506. Interestingly, we finally proved that the sorafenib resistant cells regained sensitivity for sorafenib by EZH2 intervention with miR‐124/506 overexpression or EZH2 inhibitor treatment in vitro and in vivo, which will lead to the decreased tri‐methylation at lysine 27 of histone H3 (H3K27me3) and increased acetylated lysine 27 of histone H3 (H3K27ac) levels. Therefore, we conclude that the suppression of EZH2 represents a potential target for thyroid carcinoma therapy.     

Improving membrane binding as a design strategy for amphipathic peptide hormones: 2‐helix variants of PYY3‐36

It has been hypothesized that amphipathic peptides might bind to membranes prior to activating their cognate receptors, but this has proven difficult to test. The peptide hormone PYY3‐36 is believed to perform its appetite‐suppressing actions through binding to hypothalamic Y2 receptors. It has been proposed that PYY3‐36 via its amphipathic α‐helix binds to the plasma membrane prior to receptor docking. Here, our aim was to study the implication of this hypothesis using new analogs of PYY3‐36. We first studied membrane binding of PYY3‐36. Next, we designed a series of PYY3‐36 analogs to increase membrane‐binding affinity by substituting the N‐terminal segment with a de novo designed α‐helical, amphipathic sequence. These 2‐helix variants of PYY3‐36 were assembled by solid‐phase peptide synthesis. Pharmacological studies demonstrated that even though the native peptide sequence was radically changed, highly active Y2 receptor agonists were generated. A potent analog, with a Kd of 4 nM for membranes, was structurally characterized by NMR in the membrane‐bound state, which clearly showed that it formed the expected 2‐helix. The topology of the peptide–micelle association was studied by paramagnetic relaxation enhancement using a spin label, which confirmed that the hydrophobic residues bound to the membrane. Our studies further support the hypothesis that PYY3‐36 associates with the membrane and indicate that this can be used in the design of novel molecules with high receptor binding potency. These observations are likely to be generally important for peptide hormones and biopharmaceutical drugs derived from them. This new 2‐helix variant of PYY3‐36 will be useful as a tool compound for studying peptide–membrane interactions. Copyright © 2012 European Peptide Society and John Wiley & Sons, Ltd.     

Natural regeneration as a tool for large‐scale forest restoration in the tropics: prospects and challenges

A major global effort to enable cost‐effective natural regeneration is needed to achieve ambitious forest and landscape restoration goals. Natural forest regeneration can potentially play a major role in large‐scale landscape restoration in tropical regions. Here, we focus on the conditions that favor natural regeneration within tropical forest landscapes. We illustrate cases where large‐scale natural regeneration followed forest clearing and non‐forest land use, and describe the social and ecological factors that drove these local forest transitions. The self‐organizing processes that create naturally regenerating forests and natural regeneration in planted forests promote local genetic adaptation, foster native species with known traditional uses, create spatial and temporal heterogeneity, and sustain local biodiversity and biotic interactions. These features confer greater ecosystem resilience in the face of future shocks and disturbances. We discuss economic, social, and legal issues that challenge natural regeneration in tropical landscapes. We conclude by suggesting ways to enable natural regeneration to become an effective tool for implementing large‐scale forest and landscape restoration. Major research and policy priorities include: identifying and modeling the ecological and economic conditions where natural regeneration is a viable and favorable land‐use option, developing monitoring protocols for natural regeneration that can be carried out by local communities, and developing enabling incentives, governance structures, and regulatory conditions that promote the stewardship of naturally regenerating forests. Aligning restoration goals and practices with natural regeneration can achieve the best possible outcome for achieving multiple social and environmental benefits at minimal cost.     

Evaluation of chimeric DNA vaccines consisting of premembrane and envelope genes of Japanese encephalitis and dengue viruses as a strategy for reducing induction of dengue virus infection‐enhancing antibody response

Neutralizing antibodies induced by dengue virus (DENV) infection show viral infection‐enhancing activities at sub‐neutralizing doses. On the other hand, preimmunity against Japanese encephalitis virus (JEV), a congener of DENV, does not increase the severity of DENV infection. Several studies have demonstrated that neutralizing epitopes in the genus Flavivirus are mainly located in domain III (DIII) of the envelope (E) protein. In this study, chimeric premembrane and envelope (prM‐E) gene‐based expression plasmids of JEV and DENV1 with DIII substitution of each virus were constructed for use as DNA vaccines and their immunogenicity evaluated. Sera from C3H/He and ICR mice immunized with a chimeric gene containing DENV1 DIII on a JEV prM‐E gene backbone showed high neutralizing antibody titers with less DENV infection‐enhancing activity. Our results confirm the applicability of this approach as a new dengue vaccine development strategy.